1. Field of the Invention
The present invention relates to an insertion apparatus having a flexible tube portion on a proximal end side of an insertion portion to be inserted into an examined part.
2. Description of the Related Art
An endoscope is one of insertion apparatuses and is used in a medical field, an industrial field and the like. The endoscope has an elongated insertion portion to be inserted into an examined part. The insertion portion is provided with a flexible tube having flexibility.
An endoscope used in the medical field makes it possible to perform observation of an organ and the like by inserting the insertion portion into a body. In addition, in a configuration in which the endoscope is provided with a treatment instrument insertion channel, it is possible to perform various kinds of treatments and the like by introducing a treatment instrument into a body via the channel.
In comparison, an endoscope used in the industrial field makes it possible to perform observation and inspection about presence or absence of a crack, presence or absence of corrosion and the like by inserting the elongated insertion portion into a jet engine, piping in a factory and the like.
Some endoscopes are provided with a bending portion on a distal end side of the flexible tube constituting the insertion portion. In the endoscopes provided with the bending portion, it is possible to change an orientation of the distal end portion of the insertion portion by bending the bending portion in a desired direction.
The bending portion performs a bending motion, for example, by an operator performing an operation of rotating a knob for up/down or a knob for left/right provided on the operation portion to directly pull or loosen a bending wire.
A maximum bending angle of the bending portion of an endoscope in one direction and a maximum bending angle in the other direction, which is a direction opposite to the one direction, may be different in some cases. For example, in a case of an endoscope configured such that a maximum bending angle in an upward direction is 210 degrees, and a maximum bending angle in a downward direction is 120 degrees, the burden applied on hand fingers further increases at time of causing the bending portion to bend at an angle of more than 120 degrees.
Therefore, in order to reduce the burden applied on the hand fingers, an endoscope having an electric bending mechanism portion configured to pull a bending wire using an electric mechanism to resolve the burden applied on the operator's hand fingers is proposed.
Note that, as an electric operation function portion of an endoscope for reducing the burden on an operator, electric mechanism portions such as an insertion assisting tool and a power assist mechanism portion are well-known in addition to the electric bending mechanism portion described above.
The insertion portion assisting mechanism portion has a spiral shape portion, and the spiral shape portion is rotatably disposed at a predetermined position on an outer circumferential surface of the insertion portion which is on a more proximal end side of the endoscope than the bending portion. The spiral shape portion of the insertion portion assisting mechanism portion is configured to be rotated in a spiral winding direction or in a direction opposite to the spiral winding direction around an axis of the insertion portion by driving force of a motor.
In a state in which the spiral shape portion is being rotated in the spiral winding direction, propulsion that causes the insertion portion to move forward is given to the insertion portion, the propulsion being caused by screw action caused by an outer surface of the spiral shape portion coming into contact with a body cavity wall. On the other hand, in a state in which the spiral shape portion of the insertion portion assisting mechanism portion is being rotated in the direction opposite to the spiral winding direction, propulsion that causes the insertion portion to move backward is given to the insertion portion, the propulsion being caused by screw action.
As a result, at time of performing a hand-side operation for causing the insertion portion to move forward or a hand-side operation for causing the insertion portion to move backward, the operator can obtain the propulsion that causes the insertion portion to move forward or the propulsion that causes the insertion portion to move backward, and the burden on the operator is reduced.
The power assist mechanism portion is provided with a plurality of C-shaped rings around which respective bending wires are wound, one pulley on which each of the C-shaped rings is freely disposed, and a motor configured to cause the pulley to rotate. The pulley is continuously rotated by driving force of the motor, and is configured so that, when a bending operation is performed, rotation force of the pulley is transmitted to the bending wires via the C-shaped rings.
By the rotation force of the pulley being transmitted to the bending wires via the C-shaped rings, an amount of pulling operation force is reduced in comparison with a case of directly pulling the bending wires. Thereby, it becomes possible to perform a smooth bending operation, and the burden on the operator is reduced.
International Publication No. 2014/084135 discloses an endoscope apparatus configured to transmit driving force of an electric motor, which is a driving portion, to an electric operation function portion such as an insertion portion assisting mechanism portion by a flexible driving shaft to reduce the burden on an operator.
In the endoscope apparatus, a winding direction for which torsional rigidity of the driving shaft is set high is caused to correspond to a rotation direction of the driving shaft. Therefore, in a state in which the driving shaft is being rotated in the winding direction, force that shrinks the driving shaft, in other words, force that shortens the driving shaft acts on the driving shaft. Then, the torsional rigidity of the driving shaft becomes high by the force that shortens the driving shaft acting on the shaft, and it becomes possible to certainly transmit rotational driving force.
Note that the driving shaft is configured such that one of both ends is a fixed end which is fixed, and the other end is a free end which freely moves forward and backward relative to an axial direction.
The electric bending mechanism portion of International Publication No. 2014/084135 described above is configured such that a maximum bending angle in a bending direction on one side of a bending portion and a maximum bending angle in a bending direction on the other side, which is an opposite direction, are different. Therefore, an amount of force that pulls one bending wire corresponding to the bending direction in which the maximum bending angle is large becomes larger in comparison with an amount of force that pulls the other bending wire. Therefore, the winding direction of the driving shaft and the rotation direction of the driving shaft are caused to correspond to each other, and the rotation direction of the driving shaft is caused to correspond to a rotation direction in which an amount of pulling force of a pulley is larger.
As a result, at time of causing a bending portion to bend in the bending direction in which the maximum bending angle is larger, driving force of the driving portion is efficiently and certainly transmitted by the driving shaft to cope with increase in the amount of pulling force.
On the other hand, as for the insertion assisting tool, when an insertion portion is introduced into a digestive tract of a digestive organ, resistance between an outer circumferential surface of the insertion portion and a body wall gradually increases accompanying increase in an insertion length. Therefore, larger propulsion is required at the time of inserting the insertion portion in comparison with a case of pulling out the insertion portion. Therefore, the winding direction of the driving shaft is caused to correspond to the rotation direction of the driving shaft.
More specifically, at time of inserting an insertion portion 111 of an endoscope 110 toward a depth of a large intestine 100 while obtaining propulsion, as shown in FIG. 1A, for example, a driving axle 122 of a motor 121 provided in an operation portion 115 is caused to rotate in a direction Ya1, and the rotational driving force is transmitted to a driving shaft 124 via a coupling portion 123, and the driving shaft 124 is rotated in the direction Ya1 similarly to the driving axle 122.
As a result, rotational driving force of the motor 121 is efficiently transmitted by the driving shaft 124, and a spiral shape portion 116 which is rotatable on an outer circumferential side of a flexible tube 112 is rotated in the direction Ya1, which is a clockwise direction, so that propulsion for causing the insertion portion 111 to move forward is given from the spiral shape portion 116.
Note that reference numeral 113 denotes a bending portion, and reference numeral 114 denotes a distal end rigid portion.
In an endoscope apparatus disclosed in International Publication No. 2014/084135, when the driving shaft 124 disposed in the flexible tube 112 passes, for example, through a bent portion of a sigmoid colon 101 or the like in a state in which the insertion portion 111 of the endoscope 110 is moving forward while obtaining propulsion, the driving shaft 124 is elastically deformed. When the driving shaft 124 is elastically deformed in a state of not being rotated, the driving shaft 124 is deformed such that pitches on a bending-center inner side 124i of the driving shaft 124 are narrowed, while pitches on a bending-center outer side 124o are expanded, as shown in FIG. 1B which is an enlarged view of a part A.
In comparison, when the driving shaft 124 is elastically deformed in a state in which the driving shaft 124 transmits rotational driving force to the spiral shape portion 116 and generates propulsion for moving forward, the driving shaft 124 positioned at a bending portion is closely deformed by the pitches on the bending-center inner side 124i of the driving shaft 124 being further narrowed, and the pitches on the bending-center outer side 124o are narrowed and shortened without being expanded, by the force that causes the driving shaft 124 to be shortened, as shown in FIG. 1C which is an enlarged view of the part A.